Bus ducts (or “busway”) are typically used to provide low-voltage, high-current power distribution in commercial and industrial electric power distribution applications such as industrial plants and data centers. A typical bus duct includes an elongate housing with a substantially rectangular cross section containing a plurality of conductive bus bars therein. Outlets are typically located at intervals along the bus duct to provide means for connecting loads and other devices.
A typical bus duct application may require various power distribution and monitoring capabilities. For example, in a data center application, equipment racks typically receive power from bus ducts and voltages and currents provided to such loads are often monitored by a central control system.
Loads are commonly connected to the bus duct using bug plug units that are designed to be plugged into the bus duct outlets. For example, a power distribution bus plug unit may support provision of multiple branch circuits via circuit breakers housed in the bus plug unit enclosure. Metering and other monitoring devices may also be provided in plug-in units. Such devices may include communications circuitry and may be used, for example, to provide voltage and/or current information to an external control system.
Applications often require various different combinations of such power distribution and control components. However, because each installation tends to be unique in its requirements, bus plug units are often custom made for the application. For example, a typical data center application may require power distribution for multiple branch circuits and current metering for those branch circuits. Commonly, this need is met by custom plug-in units having an enclosure housing a plurality of circuit breakers, current transformers for sensing current passing through the circuit breakers, current metering circuitry coupled to the current transformers and communications circuitry for communicating information to external control systems.